kbuild: Remove uncmd_spl logic

At this point in the conversion there should be no need to have logic to
disable some symbol during the SPL build as all symbols should have an
SPL counterpart.

The main real changes done here are that we now must make proper use of
CONFIG_IS_ENABLED(DM_SERIAL) rather than many of the odd tricks we
developed prior to CONFIG_IS_ENABLED() being available.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/include/ns16550.h b/include/ns16550.h
index 0ee5c4d..f45fc8c 100644
--- a/include/ns16550.h
+++ b/include/ns16550.h
@@ -26,7 +26,7 @@
 
 #include <linux/types.h>
 
-#if defined(CONFIG_DM_SERIAL) && !defined(CONFIG_SYS_NS16550_REG_SIZE)
+#if CONFIG_IS_ENABLED(DM_SERIAL) && !defined(CONFIG_SYS_NS16550_REG_SIZE)
 /*
  * For driver model we always use one byte per register, and sort out the
  * differences in the driver
@@ -37,10 +37,10 @@
 #ifdef CONFIG_NS16550_DYNAMIC
 #define UART_REG(x)	unsigned char x
 #else
-#if !defined(CONFIG_SYS_NS16550_REG_SIZE) || (CONFIG_SYS_NS16550_REG_SIZE == 0)
-#error "Please define NS16550 registers size."
-#elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_DM_SERIAL)
+#if defined(CONFIG_SYS_NS16550_MEM32) && !CONFIG_IS_ENABLED(DM_SERIAL)
 #define UART_REG(x) u32 x
+#elif !defined(CONFIG_SYS_NS16550_REG_SIZE) || (CONFIG_SYS_NS16550_REG_SIZE == 0)
+#error "Please define NS16550 registers size."
 #elif (CONFIG_SYS_NS16550_REG_SIZE > 0)
 #define UART_REG(x)						   \
 	unsigned char prepad_##x[CONFIG_SYS_NS16550_REG_SIZE - 1]; \
@@ -113,7 +113,7 @@
 	UART_REG(scr);		/* 10*/
 	UART_REG(ssr);		/* 11*/
 #endif
-#ifdef CONFIG_DM_SERIAL
+#if CONFIG_IS_ENABLED(DM_SERIAL)
 	struct ns16550_plat *plat;
 #endif
 };